Bob Shaw's "Light of Other Days", nominated for a Hugo award in 1967, presented the concept of slow glass: a material that takes light days, months or even years to pass through. A pane set in front of a lake for a decade, for example, could then be sold to city-dwellers wanting a nicer view. The gorgeous vista would last only 10 years, obviously, then become a delayed view of the slow glass being transported from the lake, shipped to the SlowGlass showroom, purchased and installed, before, finally, becoming a view of the bare wall behind it–as it looked ten years earlier. A more mundane applications might be to use 12-hour slow glass to provide offices and malls with permanent daylight.
Such a material still can't be bought at Home Depot, but this CGI mockup shows how we might fake it: all we'd need is a big LCD display, a camera, and lots of storage to hold months or years of HD footage.
Visualization of an outdoor installation. The monitor shows what's behind it, with 6 months delay.